LEWISTON, Maine — Three major fires in a week have destroyed nine apartment buildings, damaged others and left more than 180 people homeless, putting downtown residents on edge and leading to a crackdown on abandoned and neglected apartment houses in this former mill city.

About 100 firefighters converged early Monday to battle the latest fire, which destroyed two vacant apartment buildings and damaged a third building.

Hours later, city officials announced police, fire and public works departments will work with code enforcement officers to inspect abandoned and neglected houses in the neighborhoods where the fires occurred.

“The hammer’s coming down,” said Mayor Robert MacDonald. “We’re not going to put up with this anymore.”

Two 12-year-old boys charged with causing the first two fires remained in custody Monday after closed-door detention hearings. Six investigators from the fire marshal’s office were combing through rubble trying to determine the cause of the third blaze. Nobody was injured in any of the fires except a police officer who suffered a minor leg injury when he entered one of the buildings.

The fires, all within a few blocks of each other, put residents on edge.

One of the buildings that burned had remained occupied a month after being condemned, and several other units were vacant, raising concerns about the aging tenement housing that once served the city’s textile mill workers.

There are at least 70 condemned or vacant buildings in Lewiston, and the city has demolished about 20 other condemned buildings over the past three years, said Lewiston Police Chief Mike Boussiere.

The primary area of concern was designated as a “public priority response area.” In addition to ensuring buildings meet existing fire codes, the city will review the adequacy of the current safety standards. Also, the city was allowing residents to bring trash to the landfill for free to encourage them to get rid of piles of flammable material.

Despite the city’s actions, officials assured residents that the fires were not connected and were not the work of a serial arsonist.

“These all appear to be standalone events that happened in a short amount of time within a short distance of each other,” said Phil Nadeau, city administrator.

Other actions under consideration by the city include strengthening the city’s curfew for youngsters, who currently are allowed to stay out until 10 p.m. on weeknights and midnight on weekends, Bussiere said. In the meantime, the chief said, parents and guardians need to be keeping an eye on children.